1. Field of the Invention
This invention relates to methods of and apparatus for generating reference voltages. Accordingly, it is a general object of this invention to provide new and improved methods and apparatus of such character.
2. Description of the Prior Art
Various electrical apparatus of the prior art utilize a plurality of reference voltages, wherein one reference voltage has a unique relationship to another reference voltage, whether it be a particular fraction of the voltage or a different polarity of such voltage. Such electrical apparatus can include coders, decoders, and can include such charge redistribution circuits as disclosed in U.S. Pat. No. 4,195,282 to Frank L. Cameron, issued Mar. 25, 1980, and assigned to the same assignee as this invention.
As set forth in the aforesaid patent, various reference voltages are used including V.sub.REF, V.sub.REF /16, and -V.sub.R. A charge redistribution circuit, as set forth in the aforesaid patent, utilizes capacitors and a comparator.
Several elements of the charge redistribution circuit set forth in the foregoing patent, including the comparator and reference voltages, are of special interest. The comparator offset should be small for accurate encoding. An offset correction circuit for differential amplifiers for correction of comparator offset is disclosed in copending United States application Ser. No. 070,192, entitled "Offset Correction Circuit for Differential Amplifiers", filed Aug. 27, 1979, by Michael Cooperman, the applicant herein.